<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Demo 1</title>
</head>
<body>
<h1>demo page</h1>
</body>
<script>
function test() {
  console.log(1)
  setTimeout(function () {
// timer1
    console.log(2)
  }, 1000)
}

test();

setTimeout(function () {

// timer2
  console.log(3)
})

new Promise(function (resolve) {
  console.log(4)
  setTimeout(function () {
// timer3
    console.log(5)
  }, 100)
  resolve()
}).then(function () {
  setTimeout(function () {
// timer4
    console.log(6)
  }, 0)
  console.log(7)
})

console.log(8)
</script>
</html>
